A problem with such a cylinder lock is the so-called locking picking. This is understood as the attempt to open a cylinder lock without force without a matching key. For this purpose, special opening tools are used with which the wafer tumblers are moved out of their respective latched position against the bias up to the ring gap between the cylinder housing and the cylinder core. If in so doing a suitable torque is simultaneously exerted onto the cylinder core in the rotary opening direction, for example by means of a so-called tensioning lever, it can thus be achieved in some cases while utilizing the usually present rotary play that the wafer tumblers catch at the edge of the associated cut-out of the cylinder housing so that the cylinder core can be rotated without the desired blocking effect. In this respect, one speaks of a “setting” of the wafer tumblers which is carried out sequentially for the individual wafer tumblers.
A cylinder lock of the kind named above is known from DE 10 2007 056 739 A1. With this cylinder lock, an increased security against locking picking is achieved in that at least two of the wafer tumblers have different rotary play between the engagement section of the respective wafer tumbler and the lateral boundary of the associated cut-out in the cylinder housing located in the rotary opening direction. Whereas such a cylinder lock has proven itself in practice, there is a need to increase the security against locking picking even further.
It is an object of the invention to provide a cylinder lock of the type of a wafer tumbler cylinder which has improved security against manipulation, in particular with respect to the explained locking picking.
This object is satisfied by a cylinder lock having at least one of the wafer tumblers has a toothed zone which can be brought into engagement with a counter-toothed zone of the cylinder lock such that the wafer tumbler is blocked against a movement of the respective direction of bias when the wafer tumbler is located in the latched position and a torque is exerted onto the cylinder core in the rotary opening position.
With the cylinder lock in accordance with the invention, a respective toothed zone of one or more of the wafer tumblers cooperates with an associated counter-toothed zone of the cylinder lock through a mutual toothed engagement such that the respective wafer tumbler is blocked in the latched position when a torque is exerted onto the cylinder core in the rotary opening direction. In this respect, a shape matching is caused between the named toothed zone and the associated counter-toothed zone. The “setting” of the respective wafer tumbler explained above is thus prevented, namely in that it is not permitted at all that the respective wafer tumbler is moved out of the latched position into the unlatched position in an unauthorized manner. In this respect, the circumstance is utilized that, on a typical manipulation attempt, a torque is simultaneously exerted onto the cylinder core in the rotary opening direction, which is not the case with an intended actuation of the cylinder lock by means of the associated key. In other words, the named toothed zone of the respective wafer tumbler enters into toothed engagement with the associated counter-toothed zone as soon as, starting from the latched position of the wafer tumbler, the cylinder core is rotated in the rotary opening direction (which is possible to a specific degree due to the rotary play which is present). The respective wafer tumbler can thus not be brought into the unlatched position at all from the start within the framework of a typical picking attempt so that there is also no risk that the wafer tumbler (and in particular all wafer tumblers sequentially) is held in the unlatched position.